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Information × Registration Number 0225U004812, (0125U002901) , R & D reports Title Investigation of the mechanism of electromagnetic wave absorption in composite materials based on nickel-zinc ferrites with spinel structure popup.stage_title Виготовлення об'ємних керамічних зразків (Ni,Zn)Fe2O4 зі структурою шпінелі та дослідження їх кристалографічних, мікроскопічних та електрофізичних властивостей Head Torchyniuk Pavlo V., Доктор філософії Registration Date 19-12-2025 Organization Institute of General and Inorganic Chemistry. VI Vernadsky National Academy of Sciences of Ukraine popup.description1 The purpose of this project is to study the mechanisms of absorption of electromagnetic waves in composite materials based on nickel-zinc ferrites with a spinel structure popup.description2 Ferrites with the spinel structure Ni0.5Zn0.5Fe2O4 was synthesized by the precipitation method from aqueous solutions. It was found that the average size of the obtained particles is 34 nm. Based on the obtained particles, bulk polycrystalline samples of homogeneous ceramics with high density and an average grain size of about 10 μm were obtained. During the study of the magnetic properties of ferrite ceramics Ni0.5Zn0.5Fe2O4 with the spinel structure in a wide frequency range from 1 MHz to 50 GHz, four types of magnetic excitations were detected. The high-frequency (HF) magnetic permeability of Ni0.5Zn0.5Fe2O4 ceramics, measured in the range of 1 MHz - 2 GHz at temperatures from 100 K to 400 K, is characterized by high values of ~280 at 1 MHz and room temperature and a pronounced resonance-like dispersion at all temperatures with a wide, clearly pronounced maximum of magnetic losses in the range of 10–100 MHz. It is shown that the processes of high-frequency absorption, shielding, and attenuation of electromagnetic waves in nickel-zinc Ni0.5Zn0.5Fe2O4 are due precisely to the dynamics of magnetic domain walls. This dynamics exhibits high sensitivity even to a weak external magnetic field, which provides significant high-frequency nonlinearity of magnetic permeability and losses (at the level of ±50%, and at certain frequencies even more). In the ultrahigh-frequency (UHF) range of 2–50 GHz, three regions with minimum values of transmission and reflection coefficients (up to –30 dB) sensitive to the action of an external magnetic field were identified using a microstrip line. These regions correspond to three magnetic excitations (magnons) reflecting collective spin dynamics in the volume of the domain structure, including the natural ferromagnetic resonance (below 10 GHz) and two high-frequency magnon modes in the range of 28–44 GHz. The obtained results reveal the key mechanisms of absorption and shielding of electromagnetic waves in Ni0.5Zn0.5Fe2O4. Product Description popup.authors Oleksandr P. Fedorchuk Pavlo V. Torchyniuk Vladyslav I. Kukhar popup.nrat_date 2025-12-19 Close